Hi,
On Tue, 14 Dec 2021 at 20:28, Simon Glass sjg@chromium.org wrote:
Hi Bin,
On Wed, 1 Dec 2021 at 09:04, Simon Glass sjg@chromium.org wrote:
At present in U-Boot ACPI tables are only generated for x86 devices. It is possible to build them for ARM as well. That is the subject of this series.
The goal is to allow a rpi4 boot into Linux on ARM using ACPI rather than devicetree. This is not due to any feeling that ACPI offers advantages to the boot flow, merely because it can be done.
This goal is not yet achieved. Mostly all that is achieved is some refactoring of the ACPI code, but that is enough to get things at least building on ARM. The rpi-4 the tables are installed and the board boots to grub, where it is then unable to find the OS on the USB stick that is inserted. Further work is needed to complete things, but the ACPI changes can be applied as is.
In terms of review, please ignore the RFC/WIP patches as they need to be reworked. I am sending this series in this state to avoid sitting on patches for too long and risking duplicate effort.
The following tables are emitted with this series:
- GTDT - Generic Timer Description Table
- APIC - Multiple Advanced Programmable Interrupt Controller Description Table (some new records for ARM)
- DSDT - Differentiated System Description Table
- DBG2 - Debug Port Table 2
- FACP - Firmware ACPI Control Structure
- CSRT - Core System Resource Table
- PPTT - Processor Properties Topology Table
Missing still are:
- SSDR - Secondary System Description Table
- BGRT - Boot Graphics Resource Table
Future work is needed to:
- Finish the remaining two tables
- Get things booting nicely on rpi4
- Find a nice way to select between ACPI and devicetree at runtime
- Obtain the ACPI information from the devicetree instead of #defines
- Use the U-Boot bcm headers instead of importing new ones
- Drop the unused files
- Add some documentation
To test it, boot U-Boot on a rpi_4 with a suitable distribution.
This series is available at u-boot-dm/acpi-working
[..]
Thanks Andy for the review. I'm going to apply the first part of this tomorrow and see if we can get it in before rc1. Then I'll give the rpi bit another crack.
Regards, Simon